Whenweproducespeech,theauditorysystemreducesitsresponsetowhatitexpectstohearbasedonthe motorplan.Thisallowstheauditorysystemtoremainvigilantofexternallyproducedsoundswhilealso enablingittodetecterrorsbetweentheexpectedandactualproducedsounds.Disruptionofthisauditory feedbackmechanismduringspeechproductionhasbeenimplicatedinspeechdisorderslikepersistent developmentalstutteringandapraxiaofspeechaswellasinmentalhealthdisorderslikeautismand schizophrenia.Previousresearchhassuggestedthatmuch,butnotall,oftheauditoryfeedbackcomparisonis performedinauditorycortex.Otherauditoryfeedbackprocessingislikelyperformedbyearliersubcortical auditorystructures,buttheprecisemechanismsandlocationsofthisprocessinghasnotbeenexplicitly investigated.Inthisproject,Iproposethreeaimsforinvestigatingthestructureandfunctionofsubcortical auditorystructuresinauditoryfeedbackprocessing.?Aim1istodemonstratethecontributionof subcorticalauditorystructurestogeneralmotorinducedsuppression.?Usingtwocomplementarybrain imagingtechniques,wewilltestwhethergeneratingasoundbypressingabuttonresultsindecreasedauditory subcorticalactivitywhencomparedtopassivelisteningofthosesounds.?Aim2istotestspeechspecific subcorticalauditorymodulationbyexaminingsubcorticalactivityduringspeechformantfeedback perturbation?.Inthisexperiment,wewillalterhowparticipantshearthemselveswhiletheyspeak.Using highresolutionfunctionalbrainimaging,wewillbeabletoseeifdifferencesbetweenexpectedandactual speechfeedbackcausemoreactivityinsubcorticalauditorystructures.?Aim3istodescribethestructural connectivitybetweenauditorystructuresandtheauditoryperipheryusinghighsensitivity diffusionweightedimaging?.Thisbrainimagingtechniqueallowsustoinferhowneuronbundlesare physicallyconnectedinthebrainandextendingouttotheear.Usingexistingdatafromapowerfulnew imagingdevice,wewillexamineneuralconnectionsbetweenspecificauditoryandmotorstructuresingreater detailthanhavebeeninvestigatedbefore.Wewillalsodevelopanewmethodtotrackthecochlearnervefrom thebrainstemtotheearinordertohelpcliniciansdeterminethebesthearingimplantforhearingimpaired individuals.Overall,thisprojectwillprovidehighresolutionbrainimagingofsubcorticalauditorystructuresand theirroleincomparingexpectedtoactualselfgeneratedsounds.Ourresultswillhelpusunderstandhow faultyconnectionscancontributetospeechandmentalhealthdisordersandwillenablethedevelopmentof moreeffectivetherapiesforsuchdisordersinthefuture.
Disruptionofauditoryfeedbackmechanismsduringspeechproductionhavebeenimplicatedinspeech disorderslikepersistentdevelopmentalstutteringandapraxiaofspeechaswellasinmentalhealthdisorders likeautismandschizophrenia.Thisprojectwillprovidenovelinsightsintohowandwherethesemechanisms areperformedinthebrain,potentiallyleadingtonewtherapiesforsuchdisorders.
